Vertical tube furnace for high operating pressure

ABSTRACT

A vertical furnace for isostatic hot-pressing of powder bodies includes a cylindrical pressure chamber formed of a high pressure cylinder and end closures projecting into the cylinder. Insulation arranged in the chamber includes a cylindrical insulating wall and end insulation members. There is a seal between the upper end closure and the high pressure cylinder. In order to protect this seal against heat from the inside of the chamber, a heat resistant seal of a semi-porous material such as asbestos is arranged below the first seal in the space between the pressure cylinder and the upper end closure projecting into the cylinder.

[ July3,1973

United States Patent [191 Larker et al. I

3,606,286 9/1971 Lundstrom........................ 263/40 R VERTICAL TUBE FURNACE FOR HIGH OPERATING PRESSURE [75 Inventors: Hans Larlter; Mats Llndberg, both Primary Examiner-John J. Camby of Robemfors Sweden Attorney-Jennings Bailey, Jr.

Assignee: Allmanna Svenskn Elektrlska ABSTRACT A vertical furnace for isostatic hot Aktlebolaget, Vasteras, Sweden I wm dm w c .p p o rl-l O W m .ma h S ec e mt. u

bodies includes a cylindrical press of a high pressure cylinder and end closures into the cylinder. Insulation arran 2 7 9 l 5 1 4 8 a2 F2 Q N .mL p mp FA 1] 21 22 ged in the chamber cludes a cylindrical insulating wall and end insulation members. There is a seal between the upper end closure and the high pressure cylinder. In order to protect this seal against heat from the inside of the chamber, a heat resistant seal of a semi-porous material such as asbestos is arranged below the first seal in the space bel. 22 40 02 7 14 3 7 t n a n wo. mm Mm DU 0m Y 4 u r" u 0" n .l. r n U P u "Hm n u mm: an .ww Im mum M "u" 3 .n 7 n9 m 1 u e 2 lm cm F 3 SL M Um 11] 0 2 3 55 .l [.l

[58] Field of Search.......................... 263/40; 34/242 tween the pressure cylinder and the upper end closure projecting into the cylinder.

3 Claims, 1 Drawing Figure [56] References Cited UNITED STATES PATENTS Hablanian et Westeren..........................

PATENTEUJUL 31913 VERTICAL TUBE FURNACE FOR HIGH OPERATING PRESSURE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical furnace, preferably for isostatic hot-pressing of powder bodies, consisting of a cylindrical pressure chamber comprising a high-pressure cylinder and end closures projecting into this cylinder.

THE PRIOR ART The pressure chamber in question is internally heatinsulated by means of a cylindrical insulating wall and end insulating members which are attached to the end closures of the chamber and projecting into the cylindrical wall. The pressure chamber is, in other words, of the type shown in U.S. Pat. No. 3,628,779, in which the seal between the end closures and the high pressure cylinder is effected by sealing rings of hard rubber, for example, or plastic having a high melting point and heat-resistance.

However, even the best of such sealing rings will not stand temperatures above a certain level and certainly not the temperatures normally used in the pressure chamber. There is therefore a substantial overlap between the end insulation and the cylindrical insulating wall. However, in spite of this, the upper seal may become seriously damaged and it is presumed that this is because of the gas flows which penetrate between the upper end insulation and the cylindrical insulating wall. Such gas flows are not caused by leakage between the parts of the chamber but seem to be caused by disturbances or other phenomena in the process, in the form of gases enclosed in the billets, which are liberated. These can most closely be compared with bubbles in a bottle or on a small scale the protuberances occurring on the sun. Such gas flows can very easily penetrate between the two insulating members and cause local damage to the seal and the object of the present invention is to prevent such damage.

SUMMARY OF THE INVENTION According to the invention it is proposed to insert an extra seal below the original seal, this extra seal being made of a material for example asbestos which has sufficient heat-resistance to resist the high temperatures from the inside of the pressure chamber. Such highly heat-resistant material cannot be made with sufficient sealing capacity to replace the original seal at the pressures in question several hundred bars. On the other hand, the gas flows are prevented from directly reaching the sealing ring and the furnace according to the invention is designed in accordance with the accompanying claims.

The invention will be further described with reference to the accompanying drawing which shows a section through a furnace according to the invention, this drawing corresponding in its overall construction to FIG. 2 in the U.S. Pat. No. 3,628,779 mentioned above. For the sake of clarity the same designations are used as in this FIG. 2 of the patent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing shows a section through a high pressure chamber with end closures l3 and 23 projecting into the tube 10 of the high-pressure cylinder.

The insulating mantle 20 is built up in known manner of a number of metal tubes 29, 30 and 31 with intermediate layers 32 and 33 of insulating material and a connection ring 34. The ring 34 is connected to the annular part 21 so that the mantle 20 is suspended in the upper end closure. Between the ring 34 and the part 21 is a seal 36 which is permanent and can be efficiently cooled. The lid 25 consists of a metal dome 37 filled with insulating material, which is connected to the lid 23. Since it must be possible to lift the lid 23 with the insulation 25, there must be a small space between the dome 37 and the tube 31 in the cylindrical insulation and also between the lid 23 and the ring 21. In order to prevent gas flows which penetrate up into this space from being able to heat the lid 23 and thus the seal 24, according to the invention an extra seal 40 is inserted below the seal 24 as shown. This extra seal efficiently stops the gas flows.

It is also easy to see that the seal 40 can be applied in different ways to that shown in the drawing. For example it can be placed on the inside of the ring 34. The main thing is that an efficient barrier obstructs the gas flows in the gap between 37 and 31.

We claim:

1. Vertical furnace comprising a cylindrical pressure chamber comprising a high-pressure cylinder and end closures projecting into said cylinder, and insulation arranged in the chamber and comprising a cylindrical insulating wall and end insulation members which are attached to the end closures of the chamber and project into the cylindrical insulating wall, and a first seal between the upper end closure and the high-pressure cylinder, the invention which comprises a heatresistant seal below the first seal in the space between the pressure cylinder and the upper end closure projecting into said cylinder to protect the first seal against heat from the inside of the chamber.

2. Vertical furnace according to claim 1, in which said heat-resistant seal is of a semi-porous material.

3. Vertical furnace according to claim 1, including a ring tightly connecting the insulating wall at its upper end to the high pressure cylinder, said ring being located between the upper end closure and the high pressure cylinder, said heat-resistant seal being arranged between said end closure and said ring. 

1. Vertical furnace comprising a cylindrical pressure chamber comprising a high-pressure cylinder and end closures projecting into said cylinder, and insulation arranged in the chamber and comprising a cylindrical insulating wall and end insulation members which are attached to the end closures of the chamber and project into the cylindrical insulating wall, and a first seal between the upper end closure and the high-pressure cylinder, the invention which comprises a heat-resistant seal below the first seal in the space between the pressure cylinder and the upper end closure projecting into said cylinder to protect the first seal against heat from the inside of the chamber.
 2. Vertical furnace according to claim 1, in which said heat-resistant seal is of a semi-porous material.
 3. Vertical furnace according to claim 1, including a ring tightly connecting the insulating wall at its upper end to the high pressure cylinder, said ring being located between the upper end closure and the high pressure cylinder, said heat-resistant seal being arranged between said end closure and said ring. 